Most polymer composites commonly used in automotive or construction industries employ glass fiber as reinforcement material. However, they cause many problems in terms of energy and environment, because the glass fiber is harmful to the human body and unsuited to recycling. Recently, biocomposites using natural fiber as reinforcement material are studied in order to reduce the use of harmful glass fiber.
Being lighter than glass fiber-reinforced polymer composites by 30% or more, biocomposites are cutting-edge new material that can lead to energy saving through improved fuel efficiency (1.6%) when used for automotive parts. Further, since the natural fiber is lighter and wears machinery less as compared to the glass fiber, it can reduce energy consumption by 80% during the production. Also, the cost of the natural fiber (about 5 won/g) is only about ¼ that of the glass fiber (20 won/g). In addition, the natural fiber is lighter (density: 1.3 g/cm3) than the glass fiber (density: 2.6 g/cm3), while having superior toughness and specific modulus.
Until recently, biocomposites including powder or fiber derived from wood or non-wood natural fibers were mainly reported as cellulose-based reinforcement materials. However, the cellulose-based reinforcement materials have varying properties depending on the particular tree, the growth condition of the natural fiber, the particular portion in the tree, the growth period, or the like. Even a single fiber tends to have different composition and size in different portions. Thus, when the fiber is used as the reinforcement material without any processing, the resulting biocomposite has different properties in different parts. Further, there are concerns about the damage to the forests related with the use of the wood-derived reinforcement materials and the cultivation of non-woody plants such as flax or hemp, which are commonly used as reinforcement material in biocomposites recently.
Accordingly, studies are carried out actively over the world in order to utilize eco-friendly biomaterials as high-functional materials.